A 7-diethylaminocoumarin-based chemosensor with barbituric acid for hypochlorite and hydrazine

A novel dual-responsive colorimetric/fluorescent probe for the detection of N2H4 and ClO- and its application in environmental analysis and bioimaging

Hydrazine (N2H4) and hypochlorite (ClO-) are both reactive chemical substances extensively utilized across various industrial domains. Excessive hydrazine (N2H4) and hypochlorite (ClO-) can pose significant risks to the environment, ecosystems, and human health. In order to assess and control the environmental hazard caused by N2H4 and ClO-, there is an imperative need for efficient methods capable of rapid and precise detection of these contaminants. This paper introduces a novel dual-responsive colorimetric/fluorescent probe (MDT) for the detection of N2H4 and ClO- in environmental and biological samples. The probe exhibits turn-on fluorescent responses to N2H4 or ClO- with low detection limits (N2H4: 8 nM; ClO-: 15 nM), large Stokes shifts (N2H4: 175 nm; ClO-: 203 nm), short response time (N2H4: 4 min; ClO-: 5 s) and broad pH range (5-10). In practical applications, MDT has been successfully employed in detecting N2H4 and ClO- in water and soil samples from diverse locations. Test strips loaded with MDT offer a visual and convenient means to track N2H4 vapor and quantify N2H4 and ClO- concentrations in solutions. Finally, MDT has been utilized for sensing N2H4 and ClO- in Arabidopsis thaliana roots and living zebrafish. This study presents a promising tool for monitoring N2H4 and ClO- in the environment and living organisms.

A unique triple-channel fluorescent probe for discriminative detection of cyanide, hydrazine, and hypochlorite

Herein, the first triple-channel fluorescent probe, TTB, excited at the same wavelength (λ_ex = 360 nm) in the same sensing medium for the detection and discrimination of cyanide, hydrazine, and hypochlorite, is disclosed. While a fluorescent white color appeared (λ_em = 470 nm) with the addition of cyanide ion into the probe solution, upon addition of hydrazine and hypochlorite, green (λ_em = 503 nm) and orange (λ_em = 585 nm) fluorescent colors, respectively, were observed. A naked-eye detection for the three ions was documented. With the appearance of orange color, a mega Stokes shift of 175 nm was observed. The probe exhibited excellent selectivity and lower detection limits of 0.24 μM, 4.1 nM and 0.27 μM, and dynamic ranges of 0.0-2.0 μM, 0.0-0.05 μM and 0.0-2.0 μM for cyanide, hydrazine and hypochlorite, respectively. The sensing mechanism was investigated through computational studies before and after the addition of cyanide, hypochlorite, and hydrazine, applying density functional theory (DFT), along with the calculation of optical properties by time-dependent DFT (TD-DFT) method. The results were found to be in good agreement with the experimental values. Remarkably, the probe, TTB, successfully detected cyanide, hydrazine, and hypochlorite in complex water samples. Moreover, the detection of cyanide was successfully performed in apricot kernels, as well as hypochlorite in fruits and vegetables.

A fluorescent probe based on triphenylamine with AIE and ICT characteristics for hydrazine detection

A fluorescent probe MAM based on triphenylamine scaffold was synthesized. The electron donating group 4-methoxyphenyl and the electron acceptor dicyanoethylene were introduced on the triphenylamine scaffold to form a D-π-A fluorescent probe. The probe MAM exhibited the typical aggregation-induced emission (AIE) and intramolecular charge transfer (ICT) characteristics with the bright orange-red fluorescent emission in high water fraction (f_w ≥ 50%) and negligible emission in low water fraction. The probe MAM could detect hydrazine (N₂H₄) in DMSO-tris-HCl (10 mM, pH7.4, v/v, 3:1) with high selectivity and sensitivity. The specific reaction between MAM and hydrazine and the formation of the hydrazone blocked the ICT process, and the system emitted the cyan fluorescence which could be easily observed by naked eyes. The limit of detection (LOD) was 0.196 μM (6.25 ppb), which is lower than the US Environmental Protection Agency standard (10 ppb). The test strips prepared by the probe MAM could realize the convenient and rapid detection of N₂H₄ solution and vapor. The application of MAM in actual water samples and cells was investigated, and the results showed that MAM could sense N₂H₄ in environmental and biological aspects with potential application prospects.

A dual-responsive fluorescent turn-on sensor for sensitively detecting and bioimaging of hydrazine and hypochlorite in biofluids, live-cells, and plants

Hydrazine (N₂H₄) and hypochlorite (ClO^-) are extremely harmful to the public health, so it is vitally necessary to detect them in living system. Herein, we developed a new phenthiazine-thiobarbituric acid based dual-analyte responsive fluorescent sensor PT for visually distinguishing and detecting N₂H₄ and ClO^-. PT underwent N₂H₄/ClO^--induced CC breakage, achieving olive-drab/brilliant green fluorescence lighting-up response towards N₂H₄/ClO^- with superb specifity, ultra-sensitivity (detection limit: 15.4 nM for N₂H₄, 13.7 nM for ClO^-), and ultra-fast response (N₂H₄: <15 s, ClO^-: <20 s). The mechanisms for sensing N₂H₄ and ClO^- were investigated with support of spectral measurements and DFT investigation. Sensor based paper-strip/silica-gel device was developed for in-field supervision and on-site monitoring of gaseous and aqueous N₂H₄ and ClO^- solution. In addition, the PT was also applied for quantitatively detecting N₂H₄ and ClO^- in soil, food, plants and bio-fluids. Moreover, PT was utilized to visualize exogenous N₂H₄ and ClO^- in living plants and live-cells, demonstrating this sensor utilized as a powerful tool to detect N₂H₄ and ClO^- in biological fields.

Switching to a 'turn-on' fluorescent probe for rapid detection of hydrazine in human breast cancer cells using a test-strip

A fluorescent probe TPSBT was developed to monitor hydrazine detection with a "turn on" response, converting from a "non-responsive" probe by a simple structural modification. The probe shows very weak fluorescence due to the strong ICT process and upon treatment with hydrazine, green fluorescence appears due to the blocking of this ICT by the formation of a hydrazone. The probe TPSBT can detect hydrazine with a very low detection limit (1.22 × 10^-7 M) and within a very short time period of 50 s. Additionally, the probe is able to give a response in live cell imaging (MDA-MB 231) and also in the solid phase.

Towards developing novel and sustainable molecular light-to-heat converters

Light-to-heat conversion materials generate great interest due to their widespread applications, notable exemplars being solar energy harvesting and photoprotection. Another more recently identified potential application for such materials is in molecular heaters for agriculture, whose function is to protect crops from extreme cold weather and extend both the growing season and the geographic areas capable of supporting growth, all of which could help reduce food security challenges. To address this demand, a new series of phenolic-based barbituric absorbers of ultraviolet (UV) radiation has been designed and synthesised in a sustainable manner. The photophysics of these molecules has been studied in solution using femtosecond transient electronic and vibrational absorption spectroscopies, allied with computational simulations and their potential toxicity assessed by in silico studies. Following photoexcitation to the lowest singlet excited state, these barbituric absorbers repopulate the electronic ground state with high fidelity on an ultrafast time scale (within a few picoseconds). The energy relaxation pathway includes a twisted intramolecular charge-transfer state as the system evolves out of the Franck–Condon region, internal conversion to the ground electronic state, and subsequent vibrational cooling. These barbituric absorbers display promising light-to-heat conversion capabilities, are predicted to be non-toxic, and demand further study within neighbouring application-based fields.

The synthesis and photophysical properties of phenolic barbiturics are reported. These molecules convert absorbed ultraviolet light to heat with high fidelity and may be suitable for inclusion in foliar sprays to boost crop protection and production.